This invention relates to centralizers for well casings and in particular, to a new and improved centralizer and method of producing same suitable for shipping unassembled, and subsequent assembly in the field.
Centralizers are used on casings in wells for maintaining the casing substantially centered in the bore, particularly when there are curves in the bore. Such centralizers have been in use for many years, and consist of two collars for positioning around the well casing, typically at a joint, with the collars joined by plurality of spring bows. In the conventional centralizer, the bows are fixed to the collars, typically by welding. The resulting centralizer is relatively large and therefore requires considerable space for storage and shipping. Therefore various efforts have been made to design a satisfactory centralizer which can be stored and shipped unassembled, and be assembled in the field at the well site by use of simple hand tools such as a hammer. A variety of prior art designs are known, including those shown in the following U.S. Pat. Nos. 2,680,488; 2,738,019; 3,055,432; 3,356,147; 4,011,907; 4,042,022; 4,077,470; 4,088,186; 4,143,713; 4,219,081; 4,269,269; and 4,363,360.
Among the problems encountered in the prior art designs are the difficulty of assembly in the field by unskilled workers working under adverse conditions, and the strength and durability of the junction formed between the bows and the collars.
Accordingly, it is an object of the present invention to provide a new and improved bore hole centralizer which is easier to assemble and one having improved strength and life. A further object of the invention is to provide a new and improved method of producing a bore hole centralizer and especially a method with a simpler final assembly step.
Other objects, advantages, features and results will more fully appear in the course of the following description.